laravel chunkById 分块查询 使用时的问题

laravel chunkById 分块查询 使用时容易出现的问题

1. SQLSTATE[23000]: Integrity constraint violation: 1052 Column ‘id’ in where clause is ambiguous

使用chunkById时，单表进行分块查询，是不会出现id重复的，当用两个表进行 join 查询，如果两个表都存在ID，则会报以上的错误信息

DB::table('table1')
->select(['table1.id'])
    ->join('table2', 'table1.id', '=', 'table2.id')
    ->orderBy('table1.id')
    ->chunkById(100, function ($results) {
     
    });

如何解决：需要指定第三个参数是用哪个表的ID，例如 table1.id，

需要指定第四个参数，参数形参为 $alias,

 $lastId = $results->last()->{$alias};

意为查询出数据以后获取对应的属性，来查询最大值，相当于只要在查询的字段中取值即可, 例如 id

如果不指定第四个参数：会报 Undefined property: stdClass::$table1.id

 $alias = $alias ?: $column;

第一页执行完成以后，来查询最大的ID， $alias = table1.id

$results->last()->table1.id

查询出的值内并不会有 table1.id 的key

以下为源码：

    /**
     * Chunk the results of a query by comparing numeric IDs.
     *
     * @param  int  $count
     * @param  callable  $callback
     * @param  string  $column
     * @param  string  $alias
     * @return bool
     */
    public function chunkById($count, callable $callback, $column = 'id', $alias = null)
    {
        $alias = $alias ?: $column;

        $lastId = 0;

        do {
            $clone = clone $this;

            // We'll execute the query for the given page and get the results. If there are
            // no results we can just break and return from here. When there are results
            // we will call the callback with the current chunk of these results here.
            $results = $clone->forPageAfterId($count, $lastId, $column)->get();

            $countResults = $results->count();

            if ($countResults == 0) {
                break;
            }

            // On each chunk result set, we will pass them to the callback and then let the
            // developer take care of everything within the callback, which allows us to
            // keep the memory low for spinning through large result sets for working.
            if ($callback($results) === false) {
                return false;
            }

            $lastId = $results->last()->{$alias};

            unset($results);
        } while ($countResults == $count);

        return true;
    }
    ```

原文地址：https://blog.csdn.net/weixin_44475312/article/details/143595636

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